In electronic data processing, information is not only captured and passed on in text documents, but increasingly also in the form of image data. Frequently, information that is confidential, and is made unrecognizable before it is passed on to a third party or before it may be published, is embedded in the image data. It is provided here that the data is not stored in the underlying document file. To this end, the file of the image data may be processed manually with a suitable image processing program. After the image data file is opened with the image processing program, the relevant image regions are, for example, blackened or cut out with suitable functions of the image processing program. The process ends by storing the image data in a document file again.